This invention relates to photocopying optical systems, and more particularly to an optical system for substantially doubling the capacity of a photocopying apparatus.
By way of background, it is generally desirable to maximize the capacity or machine throughput of a photocopying apparatus for any given process speed. Heretofore, this has been accomplished in copiers and duplicators by processing in the "landscape" rather than "portrait" mode. In a scanning environment, this refers to scanning of the original object from one long edge to the other, the scan travel being therefore along the short dimension. Correspondingly, the image is laid down on the photoreceptor and developed from one long edge to the other along the shorter edge dimension. It will be apparent that, for a given speed of photoreceptor, such an image is generated and developed faster than one which is scanned and laid down on the photoreceptor in the portrait mode, i.e., scanning in the longer direction from short edge to short edge.
From the foregoing step from portrait to landscape operation, a natural next step was to enlarge the size of the object station so as to accommodate an original object of, for example, 11 .times. 17 inches. This of course is equivalent to two adjacent 81/2 .times. 11 inches sheets. Scanning and otherwise processing of an 11 .times. 17 inches original in the landscape mode then, becomes the equivalent of simultaneous processing of two adjacent 81/2 .times. 11 inches originals in the portrait mode.
The several stages just described are illustrated in FIGS. 1a, 1b, and 1c. The progression may seem quite straightforward, simply providing more photoreceptor area and arranging the object in an optimum way to maximize its use. However, FIG. 1c also illustrates an inherent problem. That is, if the original object to be copied is not a "book" of several documents but a single original, then there is not only a zero gain in capacity or throughput in the apparatus but also an attendant waste of 50% of the copy paper, since a blank sheet will result from each scan of the blank part of the object area.
It is an object of this invention to provide a photocopying optical system which is capable of alternative modes of operation: to create adjacent images of adjacent objects or double images from a single object.